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Poor Homologous Synapsis 1 Interacts with Chromatin but Does Not Colocalise with ASYnapsis 1 during Early Meiosis in Bread Wheat.

Khoo KH, Able AJ, Able JA - Int J Plant Genomics (2012)

Bottom Line: Furthermore, TaPHS1 does not appear to colocalise with the asynapsis protein (TaASY1) suggesting that these proteins are probably independently coordinated.Significantly, the data from the DNA-binding assays and 3-dimensional immunolocalisation of TaPHS1 during early meiosis indicates that TaPHS1 interacts with DNA, a function not previously observed in either the Arabidopsis or maize PHS1 homologues.As such, these results provide new insight into the function of PHS1 during early meiosis in bread wheat.

View Article: PubMed Central - PubMed

Affiliation: School of Agriculture, Food & Wine, Waite Research Institute, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, SA, 5064, Australia.

ABSTRACT
Chromosome pairing, synapsis, and DNA recombination are three key processes that occur during early meiosis. A previous study of Poor Homologous Synapsis 1 (PHS1) in maize suggested that PHS1 has a role in coordinating these three processes. Here we report the isolation of wheat (Triticum aestivum) PHS1 (TaPHS1), and its expression profile during and after meiosis. While the TaPHS1 protein has sequence similarity to other plant PHS1/PHS1-like proteins, it also possesses a unique region of oligopeptide repeat units. We show that TaPHS1 interacts with both single- and double-stranded DNA in vitro and provide evidence of the protein region that imparts the DNA-binding ability. Immunolocalisation data from assays conducted using antisera raised against TaPHS1 show that TaPHS1 associates with chromatin during early meiosis, with the signal persisting beyond chromosome synapsis. Furthermore, TaPHS1 does not appear to colocalise with the asynapsis protein (TaASY1) suggesting that these proteins are probably independently coordinated. Significantly, the data from the DNA-binding assays and 3-dimensional immunolocalisation of TaPHS1 during early meiosis indicates that TaPHS1 interacts with DNA, a function not previously observed in either the Arabidopsis or maize PHS1 homologues. As such, these results provide new insight into the function of PHS1 during early meiosis in bread wheat.

No MeSH data available.


Q-PCR profiling of TaPHS1 shows that it is expressed during meiosis. While the amount of TaPHS1 mRNA transcript is low, it has higher levels of expression during premeiosis when compared to the other stages of meiosis examined in Chinese Spring wild type (open bars). In the ph1b mutant (black bars), TaPHS1 is upregulated between 1.5- and 2-fold across the time points analysed. Normalisation of the Q-PCR data was performed against three control genes (actin, GAPdH, and cyclophilin) as per Crismani et al. [36]. Data represent the means ± SE of three replicates. Units on the y-axis represent normalised mRNA transcript μL−1.
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fig4: Q-PCR profiling of TaPHS1 shows that it is expressed during meiosis. While the amount of TaPHS1 mRNA transcript is low, it has higher levels of expression during premeiosis when compared to the other stages of meiosis examined in Chinese Spring wild type (open bars). In the ph1b mutant (black bars), TaPHS1 is upregulated between 1.5- and 2-fold across the time points analysed. Normalisation of the Q-PCR data was performed against three control genes (actin, GAPdH, and cyclophilin) as per Crismani et al. [36]. Data represent the means ± SE of three replicates. Units on the y-axis represent normalised mRNA transcript μL−1.

Mentions: Quantitative real-time PCR (Q-PCR) profiling of TaPHS1 in wild type Chinese Spring shows that it has low transcript abundance during meiosis (Figure 4). Although TaPHS1 is expressed in wheat anther tissue throughout all stages of meiosis examined and beyond, statistical analysis suggests that expression is higher during premeiotic interphase and immature pollen. Between the pooled stages of leptotene-pachytene and diplotene-anaphase I, there is no statistically significant difference in TaPHS1 expression. Given that Boden et al. [20] demonstrated that the TaASY1 transcript was significantly upregulated in a ph1b background when compared to wild type (approximately 20-fold), we also investigated transcription levels of TaPHS1 in the ph1b mutant. While not as dramatic as that reported for TaASY1 in Boden et al. [20], TaPHS1 was also upregulated in the ph1b mutant when compared to wild type but by between 1.5-fold (premeiosis) and 2-fold (leptotene-pachytene) (Figure 4).


Poor Homologous Synapsis 1 Interacts with Chromatin but Does Not Colocalise with ASYnapsis 1 during Early Meiosis in Bread Wheat.

Khoo KH, Able AJ, Able JA - Int J Plant Genomics (2012)

Q-PCR profiling of TaPHS1 shows that it is expressed during meiosis. While the amount of TaPHS1 mRNA transcript is low, it has higher levels of expression during premeiosis when compared to the other stages of meiosis examined in Chinese Spring wild type (open bars). In the ph1b mutant (black bars), TaPHS1 is upregulated between 1.5- and 2-fold across the time points analysed. Normalisation of the Q-PCR data was performed against three control genes (actin, GAPdH, and cyclophilin) as per Crismani et al. [36]. Data represent the means ± SE of three replicates. Units on the y-axis represent normalised mRNA transcript μL−1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig4: Q-PCR profiling of TaPHS1 shows that it is expressed during meiosis. While the amount of TaPHS1 mRNA transcript is low, it has higher levels of expression during premeiosis when compared to the other stages of meiosis examined in Chinese Spring wild type (open bars). In the ph1b mutant (black bars), TaPHS1 is upregulated between 1.5- and 2-fold across the time points analysed. Normalisation of the Q-PCR data was performed against three control genes (actin, GAPdH, and cyclophilin) as per Crismani et al. [36]. Data represent the means ± SE of three replicates. Units on the y-axis represent normalised mRNA transcript μL−1.
Mentions: Quantitative real-time PCR (Q-PCR) profiling of TaPHS1 in wild type Chinese Spring shows that it has low transcript abundance during meiosis (Figure 4). Although TaPHS1 is expressed in wheat anther tissue throughout all stages of meiosis examined and beyond, statistical analysis suggests that expression is higher during premeiotic interphase and immature pollen. Between the pooled stages of leptotene-pachytene and diplotene-anaphase I, there is no statistically significant difference in TaPHS1 expression. Given that Boden et al. [20] demonstrated that the TaASY1 transcript was significantly upregulated in a ph1b background when compared to wild type (approximately 20-fold), we also investigated transcription levels of TaPHS1 in the ph1b mutant. While not as dramatic as that reported for TaASY1 in Boden et al. [20], TaPHS1 was also upregulated in the ph1b mutant when compared to wild type but by between 1.5-fold (premeiosis) and 2-fold (leptotene-pachytene) (Figure 4).

Bottom Line: Furthermore, TaPHS1 does not appear to colocalise with the asynapsis protein (TaASY1) suggesting that these proteins are probably independently coordinated.Significantly, the data from the DNA-binding assays and 3-dimensional immunolocalisation of TaPHS1 during early meiosis indicates that TaPHS1 interacts with DNA, a function not previously observed in either the Arabidopsis or maize PHS1 homologues.As such, these results provide new insight into the function of PHS1 during early meiosis in bread wheat.

View Article: PubMed Central - PubMed

Affiliation: School of Agriculture, Food & Wine, Waite Research Institute, The University of Adelaide, Waite Campus, PMB1, Glen Osmond, SA, 5064, Australia.

ABSTRACT
Chromosome pairing, synapsis, and DNA recombination are three key processes that occur during early meiosis. A previous study of Poor Homologous Synapsis 1 (PHS1) in maize suggested that PHS1 has a role in coordinating these three processes. Here we report the isolation of wheat (Triticum aestivum) PHS1 (TaPHS1), and its expression profile during and after meiosis. While the TaPHS1 protein has sequence similarity to other plant PHS1/PHS1-like proteins, it also possesses a unique region of oligopeptide repeat units. We show that TaPHS1 interacts with both single- and double-stranded DNA in vitro and provide evidence of the protein region that imparts the DNA-binding ability. Immunolocalisation data from assays conducted using antisera raised against TaPHS1 show that TaPHS1 associates with chromatin during early meiosis, with the signal persisting beyond chromosome synapsis. Furthermore, TaPHS1 does not appear to colocalise with the asynapsis protein (TaASY1) suggesting that these proteins are probably independently coordinated. Significantly, the data from the DNA-binding assays and 3-dimensional immunolocalisation of TaPHS1 during early meiosis indicates that TaPHS1 interacts with DNA, a function not previously observed in either the Arabidopsis or maize PHS1 homologues. As such, these results provide new insight into the function of PHS1 during early meiosis in bread wheat.

No MeSH data available.